1. Field of the Invention
The field of the invention relates to the regulation of the growth of aquatic weeds in canals, rivers, ponds, lakes, and impoundments.
2. Description of the Prior Art
The problems of controlling or regulating the growth of organisms in aqueous systems are serious and growing in severity. Submerged aquatic weeds, for example, cause major problems in water distribution and irrigation systems. The growth of such weeds in irrigation canals greatly reduces the conductivity and capacity of such systems with resulting substantial economic loss. Large sums are spent in the mechanical and other methods of removal of weed growths from irrigation canals, especially in the western parts of the United States. Because of the great difficulties involved in the mechanical removal of weeds and other undesired forms of aquatic life from irrigation canals, ponds, lakes, impoundments, etc., it has been proposed to utilize chemical control. Accordingly, various types of chemicals have been added to such bodies of water.
However, with the growing emphasis on conservation, current efforts are directed toward regulating the growth, that is, limiting or inhibiting the amount of growth accomplished by the naturally occurring submerged or floating aquatic weeds without killing those weeds. This approach is being taken in order to continue to provide the natural environment for fish and other forms of marine life. A further reason is to avoid the masses of dead and rotting aquatic weeds which result when said weeds are killed by means of an aquatic herbicide, since the decomposition of the weeds decreases the amount of available oxygen present in the water. Such decaying matter, when it occurs in reservoirs and/or streams from which drinking water for cities is obtained, makes purification of the water more difficult. Such decaying vegetation also gives off an unpleasant odor when it collects in a body of water. Thus, a control of the amount of growth, rather than a destruction of the submerged aquatic weeds, serves to overcome both pollution of the water and pollution of the air.
In the prior art, Krumkalns et al., U.S. Pat. No. 3,655,359 (Apr. 11, 1972), teach the use of substituted 3-pyridylmethanes for eliminating germinating weed grasses and broadleaf weeds selectively from crop plants such as corn, cotton, and soybeans, and their close relatives in the plant kingdom, and also for inhibiting the growth of suckers on tobacco plants. None of the compounds in the reference have fluoroalkoxy substituents, and there is no teaching that if the compounds disclosed therein were modified to give the compounds disclosed in the instant application, such compounds would thereby possess aquatic growth regulating properties.
Also in the prior art, Krumkalns et al., U.S. Pat. No. 3,744,988 (July 10, 1973), teach the use of substituted 3-pyridylmethanes in a method for inhibiting sucker growth to tobacco plants. This patent is a division of U.S. Pat. No. 3,655,359, supra, and includes in its disclosure many of the same compounds disclosed therein. There are no fluoroalkoxy-substituted 3-pyridine compounds disclosed in this reference, either, nor teaching that would make their utility as aquatic growth regulators obvious.
Van Heyningen, U.S. Pat. No. 3,396,224 (Aug. 6, 1968), teaches a method of controlling fungi pathogenic to plants by contacting the fungus-susceptible plant with a fungicidal amount of a 3pyridylmethane derivative, mainly a 3-pyridinemethanol. No fluoroalkoxy-substituted 3-pyridine compounds are taught in this reference, nor are there any suggestions that such substituted pyridine compounds would be useful as aquatic growth regulators.
Van Heyningen et al., U.S. Pat. No. 3,397,273 (Aug. 13, 1968), teaches and claims a method for protecting plants from attack by phytopathogenic fungi by treating the plants with a fungicidally-effective amount of a 3-pyridylmethane. No fluoroalkoxy-substituted 3-pyridine compounds are taught in this reference, and there are no suggestions that such compounds would be useful as aquatic growth regulators.
Another prior art reference is Belgian Pat. No. 816,245 (Nov. 20, 1974), which teaches the preparation, inter alia, of the fluoroalkoxy-substituted 3-pyridinemethanol compounds found useful in the present invention. This Belgian reference teaches the utility of the disclosed compounds as herbicides, plant fungicides and as terrestrial plant growth regulators, with activity being shown in tests on soybean, chrysanthemum, and turf. There is no teaching or suggestion that the compounds would have utility as aquatic plant growth regulators.
Another reference is German Pat. No. 1,935,292, also identified by Derwent No. 04548S, which patent teaches and claims a means for controlling plant growth, that is, restraining growth and influencing the habits of higher plants, influencing blossom and fruit formation, checking the growth of grass, and the like, using tri-arylmethylimidazoles, -pyrazoles, and -triazoles, or their salts. One of the aryl groups is taught as pyridyl. The reference does not appear to include use on aquatic weeds or plants.
Yet another reference is British Pat. No. 1,274,578, also identified by Derwent No. 23143S. This reference teaches plant growth regulators containing N-benzylimidazoles, wherein one of the substituents is a pyridyl group. These compounds are alleged to be plant growth regulators capable of inhibiting or accelerating growth, flowering and fruiting, according to the amount applied. Certain of the compounds are also alleged to be plant fungicides and bactericides. Neither of these last two references have any fluoroalkoxy substituents mentioned in them for attachment to the pyridine nuclei therein.